I just went through this. M104 wagon black on black in Tucson. Replaced the entire cooling/hvac system; Nissens radiator/condenser, Graf water pump, hoses, 82c thermostat, mb water switches, Denso compressor and drier+switches, evap, new spal aux fans, zerex 50/50. Everything. @110F my temps still went to 105f. What worked for me was replacing the new Behr fan clutch with the upated Sachs one.

Now even with super high ambients my temperatures never go above 95f even with the a/c running at idle. Incidentally I’m running r154a as well and getting 44f at idle and 36f freeway which I think is also helping as far as condenser heat dissipation.

Might want to check into the updating fan clutch or go the Spal electric puller way.